The Geotools.Net library is set of .Net classes useful when handing geographic information. The classes implement the geometry model defined in the OpenGIS Consortium Simple Features Specification for Java/COM.

Xconq is an engine for turn-based strategy games. Variety of game genres run under Xconq: historical, sci-fi, fantasy, and modern. AIs. Network games. Multiple UIs and platforms. Easy-to-learn game design language. Large games library available

NOTE - All project resources are now hosted at http://qgis.org. Quantum GIS (QGIS) is a Geographic Information System (GIS). QGIS supports common vector and raster formats, including Shapefiles, PostGIS, GRASS, GeoTiff, TIFF, JPG, and many more.

CacheMagnet geocaching software lets you edit, map, and download GPX waypoint files to your GPSr or IPod Nano. Maps and reports can be printed to take with you in the field. The map supports zoom and pan, road map, satellite map and birds-eye.

GPSBabelWrapper allows the rest of us to use rich functionality of GPSBabel via familiar Windows interface. It only builds a command line and calls GPSBabel.
GPSBabelWrapper is similar in goals to Gebabbel and to the standard GPSBabelGUI.exe

QuakeMap GPS mapping program - see quakemap.com and download free trial there. This is a complete Open Source version (no different in features than the commercial version). You can compile it in Visual Studio 2008, enhance it to fit your needs.

The nofdp IDSS is an open source application for modeling flood control measures and 1D hydrodynamic flood simulation. Additional modules for ecological and spatial analysis, multicriteria evaluation and communication are included.

KalypsoBASE is a Desktop-GIS built on Eclipse. It's focus lies on modelling gis data using GML Application-Schemata. Features contain generic dialogs based on GML, maps based on OGC's SLD, and other tools like a charting framework or API for timeseries

KartoMNT is a free software of height model digitalization.
This software allows you to create your own Digital Height Models (DHM) with a simple map. Then you'll be able to visualize DHMs with the KartoMNT 3D viewer.

Konverting the GIS-Format 'EDBS' to Spatial-Database 'PostGIS' using the 'Well Known Text'-Interface.
EDBS is a German Fileformat from ALK (Automatisierte Liegenschaftskarte).
So this GIS can be used for UNM-Mapserver and otehr OGC-conform GIS-Programms.
Update: After ALK in Germany ist replaced by ALKIS, edbs2wkt will not be further developed.
Use http://postnas.org (gdal/ogr) for ALKIS-Interface-Format "NAS".

AVPython embeds the Python programming language within ArcView GIS 3.x. This project will also encompass efforts to build a similar bridge between Python and ArcObjects. An integrated, redistributable Python / PyWin32 setup wizard is also published here.

G2C (Geospatial to Civil)
The LandGML Interoperability Experiment initiated by Autodesk, U.S. Army Corps of Engineers Engineering Research and Development Center, and Galdos Systems. this open source tool transforms LandGML into LandXML documents.